4

AN7124

ICs for Audio Common Use

s Application Note

1.Voltage gain

The close loop gain of AN7124 is fixed at 45 dB(typ.)

)

2.Standby function

Standby is ON when Pin1 is set to "L". By applying a 5 V to the standby pin, transistor Q1 will be turned ON to

provide a constant current (I) for driving other parts of the circuit. The RC is to create a TIME CONSTANT for the

standby pulse during charging and discharging.

Threshold voltage (at Pin1) :

ON

<2.8 V<OFF

3.Muting

By controlling Pin2 from "H" to "L", the mute function is set from ON to OFF. When Pin2 is floating, DC

≈ 0.02

V. The threshold is set

≈ 2.8 V. The RC is to create a TIME CONSTANT for the mute pulse during charging and

discharging.

Threshold voltage (at Pin2) :

10 % mute

= 1.5 V

90 % mute

= 2.8 V

15 k

Ω

84

Ω

R

C

1

Stb

Off

On

I

5 V

R

C

2

Bias

Mute

Off

On

5 V